303 research outputs found
Compact spaces generated by retractions
We study compact spaces which are obtained from metric compacta by iterating
the operation of inverse limit of continuous sequences of retractions. We
denote this class by R. Allowing continuous images in the definition of class
R, one obtains a strictly larger class, which we denote by RC. We show that
every space in class RC is either Corson compact or else contains a copy of the
ordinal segment . This improves a result of Kalenda, where the
same was proved for the class of continuous images of Valdivia compacta. We
prove that spaces in class R do not contain cutting P-points (see the
definition below), which provides a tool for finding spaces in RC minus R.
Finally, we study linearly ordered spaces in class RC. We prove that scattered
linearly ordered compacta belong to RC and we characterize those ones which
belong to R. We show that there are only 5 types (up to order isomorphism) of
connected linearly ordered spaces in class R and all of them are Valdivia
compact. Finally, we find a universal pre-image for the class of all linearly
ordered Valdivia compacta.Comment: Minor corrections; added two statements on linearly ordered compacta.
The paper has 21 pages and 2 diagram
Two lipid-anchored cAMP-binding proteins in the yeast Saccharomyces cerevisiae are unrelated to the R subunit of cytoplasmic protein kinase A
A new characterization for the m-quasiinvariants of S_n and explicit basis for two row hook shapes
In 2002, Feigin and Veselov defined the space of m-quasiinvariants for any
Coxeter group, building on earlier work of Chalykh and Veselov. While many
properties of those spaces were proven from this definition, an explicit
computation of a basis was only done in certain cases. In particular, Feigin
and Veselov computed bases for the m-quasiinvariants of dihedral groups,
including S_3, and Felder and Veselov computed the non-symmetric
m-quasiinvariants of lowest degree for general S_n. In this paper, we provide a
new characterization of the m-quasiinvariants of S_n, and use this to provide a
basis for the isotypic component indexed by the partition [n-1,1]. This builds
on a previous paper in which we computed a basis for S_3 via combinatorial
methods.Comment: 26 pages, uses youngtab.st
Cyclic AMP Receptor Protein from Yeast Mitochondria
We have identified and characterized a cyclic AMP receptor protein in mitochondria of the yeast Saccharomyces cerevisiae. The binding is specific for cyclic nucleotides, particularly for cyclic AMP which is bound with high affinity (Kd of 10(-9) M) at 1 to 5 pmol/mg of mitochondrial protein. The mitochondrial cyclic AMP receptor is synthesized on cytoplasmic ribosomes and has an apparent molecular weight of 45,000 as determined by photoaffinity labeling. It is localized in the inner mitochondrial membrane and faces the intermembrane space. Cross-contamination of mitochondrial inner membranes by plasma membranes or soluble cytoplasmic proteins is excluded
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